1. Field of the Invention
An important component in the diagnosis and treatment of disease is the ability to determine the nature of the pathogen, the strain of the pathogen, the affected cells, the presence of abnormal proteins, and the like, as well as the ability to determine the level of bound or unbound drug in a physiological fluid, during the treatment of a disease. Determination of drugs is also of interest in cases of drugs of abuse, the ingestion of toxins, and the like. Also, in many instances, one is concerned with the presence of specific receptors, particularly antibodies, in relation to disease diagnosis or determining the health of the individual. Assays also find use in blood typing, HLA typing and the determination of other phenotypic products.
In many situations, one is concerned with detecting an extremely small amount of material in a complex composition containing a variety of other materials, which may be of similar or different structure. In order to detect the presence of a specific material, antibodies or other receptors have been employed which bind specifically to a determinant site. This complex formation between a ligand and receptor has found extensive use for a qualitative or quantitative determination of the presence of a defined determinant site in a sample.
More recently, there is increasing interest in the ability to detect pathogens, mutations and genetic related diseases by polynucleotide hybridization. Since there will frequently be concern in detecting unique sequences which are only a minute part of the total DNA and/or RNA, sensitive methods will be necessary to ensure accuracy of results.
As the need has grown to detect an ever increasing variety of analytes, there has been increased efforts to develop new techniques with enhanced sensitivity, ease of operation, opportunity for automation, reproducibility and low incidence of error.